internal SongRequest(Echonest echonest) { _echonest = echonest; }
internal ArtistRequest(Echonest echonest) { _echonest = echonest; }
internal SongRequest(Echonest echonest) { _echonest = echonest; }
internal ArtistRequest(Echonest echonest) { _echonest = echonest; }
internal PlaylistRequest(Echonest echonest) { _echonest = echonest; }